Harmonica - how much I do not know

What has become clear today is there is a lot I don't know about Harmonica's and at the moment I am not sure where to look or possibly where to start. Having watched a number of videos I now appreciate i will have to modify my peartrees to be more specific about their contents such as "bending" , "pucker or tongue blocking". I guess the best players can use all of these techniques and so in time I will have to try them all but at the moment I am not sure where to start. My inclination is to focus on the single note - I assume all music is fundamentally made up of single notes or collections of such notes but at the moment I find it difficult to create a single note because the holes are so close together. i will persevere.